Study of the operation of a combine harvester cleaning system with a sieve screw separator in the conditions of operation on slopes

The article presents the results of studies of a cleaning system with a sieve screw separator in operation conditions of a combine harvester on slopes. The grain heap in the proposed cleaning system is moved by screws, which ensures uniform feeding of the grain heap to the upper sieve with longitudinal tilts of the combine. Autonomous operation of the screws reduces the uneven distribution of grain heaps across the width at the beginning of the upper sieve of the cleaning system. Preliminary separation of grain reduces the grain flow to the upper sieve by more than 60%. Laboratory studies have shown a decrease in grain loss with a transverse tilt of the combine of 8 degrees from 1.17% in the compared treatment system to 0.75% in the treatment system with a sieve screw separator. An additional reduction in grain losses was achieved by installing longitudinal partitions with a height of 0.13 m on the upper sieve, preventing the grain heap from shifting sideways on the upper sieve. The theoretical coefficient of variation in the grain heap layer thickness at the end of the upper sieve is 0.18. Grain losses in the proposed cleaning system, calculated by the mathematical model of separation, amounted to 0.14%, which is 8 times lower than the compared cleaning system.